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Eagletac has recently updated their series of high-output lights, bringing several new classes to the fold. In this review, I will be looking at the MX25L4 Turbo (SST-90 version)  a 4x18650 thrower.

To put this model in context, I have previously reviewed the standard-head version of the Eagletac MX25L2 (with SST-90 emitter), and the subsequent Turbo head option a short time later. Like the new MX25L4 Turbo, you also have a choice of Luminus emitters on the MX25L2  and I subsequently reviewed the MX25L2 Turbo SBT-70 version.

For those of you not up-to-date on your Luminus emitters, I'll run through all the options when I discussed the build of this particular model. As always, I plan to do detailed comparison testing to other lights in this class.

Manufacturer Reported Specifications:
(note: as always, these are simply what the manufacturer provides  scroll down to see my actual testing results).

As with other recent Eagletac models, the MX25L4 Turbo comes securely packaged in an Eagletac cardboard box. The light comes in a soft fabric pouch with a drawstring. Included accessories are a paracord wrist lanyard, extra o-rings, four CR123A anti-rattle magazine holders, tailcap with secondary switch, manual, and warranty card.

The MX25L4 series carries on the robust tradition of the larger MX25 and SX25 series lights. The MX25L4 Turbo is a solid model, with good weight and decent hand ergonomics. The Turbo head version of the MX25L4 makes the light somewhat unwieldy to carry (i.e., there is no holster supplied), but this is no worse than many of its 4x18650 Turbo competitors (e.g. Supbeam K50, Fenix TK61, etc.).

As always for Eagletac, knurling is of reasonably high aggressiveness, and is present over the entire battery tube/handle, with some additional bands on the head. Anodizing is glossy black, hard anodized (i.e., type III). There were a couple of small chips in the anodizing on the bottom concentric ring in the head on my sample. There are a fair number of labels, and all are bright and clear (sharp white against the black background).

Similar to the recent SX25L3, the MX25L4 Turbo doesn't use a battery carrier, but instead has cut-out wells for the cells. Unlike the SX25L3, the cells are not arranged in continuous series, but rather in a 2s2p arrangement. Connection is made by contacts on a connector piece in the tailcap. Technically, this design means you could run the light on just 2x18650 (or 4xCR123A) if you needed to  but I wouldn't recommend this on anything but the lowest levels. The tailcap connector can spin freely, and locks in place to a set of holes in the body that line up with rods in the tailcap.

Screw threading on the tailcap is traditional triangular cut, and is anodized. But this doesn't mean you can lock out the light  there is also a pin that allows a current path between the head and the tailcap. As a result, it really is the tension on the springs that determines the contact, and hence no lock-out is usually possible. Thread feel is very smooth on my sample. The extra signal path is required for the secondary tailswitch to operate.

As with other recent Eagletac lights that use a head switching mechanism, there are a series of spring-mounted pins in the head that are required to interpret the output state of the light. The thickness and quality of these pins looks similar to my SX25L3, which were improved compared to some of the earlier MX25L2 models I tested.

The electronic switch in the head controls on-off when the tailcap is connected, with output mode selection and programming controlled by head twist. This is the same as the other recent SX25/MX25xx-series lights, although the design of the contact points in the head can vary somewhat (scroll down for a UI discussion). Side-switch feel is good for an electronic switch  there is a reasonable traverse, and the action is firm. Grip is good with the texturized rubber button cover.

My MX25L4 Turbo came with the secondary tailswitch tailcap, which allows you to turn the light on/off at either the head switch or the tailswitch (i.e., switch function is identical). The MX25L4 can tailstand, and there is a wrist lanyard strap attachment point on the side. Note there is no real anti-roll feature, and the light can roll easily when on its side.

Screw threads in the head region are square-cut (and thick). This is where mode switching occurs, as with the other recent Eagletac lights, so you need to keep the contact surfaces here scrupulously clean.

The MX25L4 Turbo reflector is very smooth and shiny, contributing to excellent throw. Overall dimensions are similar to the Turbo option of the MX25L2 series  although I find the MX25L4 Turbo head to be slightly wider at its max opening. The difference between the MX25L4 Turbo models really comes down to the emitter choice.

To put what you are looking at above into context, the base SST-90 emitter has a relatively large footprint, and a typical big round emitter dome. Note that this dome is distorting the true size of the emitter somewhat in the pics - it isn't really quite that big.

The SBT series of emitters (SBT-70 and SBT-90) are based off the same SST-90 die, but both lack the large dome. They do have a covering, but it is very thin over the emitter die. This results in improved light transmission for focusing, but winds up reducing the maximum luminous flux possible with this emitter class.

The SBT-70 is basically a "rounded off" version of the SBT-90 (which has the same actual die size as the SST-90  3x3mm). By making the die round, you can again focus it better for throw. Although you would of course expect some loss of output for this maneuver (i.e., since you are in essence removing parts of the die).

Eagletac isn't the only maker that provides the option to select between the various SST-90/SBT-90/SBT-70 versions. For additional context and comparison between the various emitter types (and close-ups of the emitters), please check out my MX25L2 Turbo SBT-70 review (for a SST-90/SB-70 comparison), Skilhunt K30 SBT-90 review (for SST-90/SBT-90 comparison), and Olight SR95SUT review (for a SST-90/SBT-90/SBT-70 comparison).

User Interface

The MX25L4 Turbo interface is very similar to other SX25/MX25xx series lights. Turn the light on/off by the electronic switch. Press and hold for momentary, press-release (i.e. click) for locked-on.

There are four output levels controlled by how loose/tight the head is (i.e., the four levels are accessed in sequence from head fully tight).

Note that as with other Eagletac lights that use this interface, the physical turning distance between the levels is not equidistant. As soon as you loosen past fully tight, you drop down to the second level. You drop down again to the third level quickly after a partial turn, and similarly again for the fourth level after another turn. By ~100 degree turn on my sample, you are into the fourth mode. This means that you can jump to the lower modes very quickly. The light remains in the lowest mode until you complete almost a full turn from fully tight (at which point the light shuts off).

There are two possible groups of output modes available - Regular (100% > 45% > 8% > 1%, in sequence from fully tight) and Tactical (100% > 10% > Strobe I > Strobe II, in sequence). You can switch between the two groups by turning the light on max (fully tight) and loosening the head to the second level and then back to tight, repeating this sequence five times in five seconds.

You can access a momentary Turbo from any head position by a press-and-hold of the switch when On. You can similarly access strobe at any time by a double press and hold (i.e. click and press-hold). Strobe is accessible even from Off with this maneuver. Simply release the switch to return to your previous head-set level.

To access the hidden auxiliary modes, do a quick loosen-tighten twist of the head (from first level tight to third or fourth level and back again). Repeat this twist to advance through the modes. Mode sequence is: Strobe I > Strobe II > Hi-Flash > SOS I (fast) > SOS II (slow) > Beacon > Lo-Flash, in repeating sequence. Turn off the light or loosen the head to quit the hidden modes. FYI, I have found that they have relaxed the timings for these maneuvers, compared to earlier lights. You no longer have to frantically twist the head  an even motion will do the trick. In fact, it works more consistently if you take your time.

On some of SX25/MX25xx series lights, there is an option to reduce the "energy saving feature" (when the light reduces output after 200 seconds in Max). The MX25L4 series is similar to the MX25L2 in that there is no option here  you will always get a 20% drop in output after 200 secs. Of course, you can always turn the light off-on to restart the max output mode.

The secondary tailswitch functions exactly the same as the main switch in the head.

Video:

For more detailed information, including general build and user interface, please see my video overview:

As with all my videos, I recommend you have annotations turned on. I commonly update the commentary with additional information or clarifications before publicly releasing the video.

Strobe

As before, there is no sign of PWM at any output level on the MX25L4  I presume all levels are current-controlled.

Strobe I:

The main strobe is a high frequency strobe, measured at 13.7 Hz on my MX25L4.

Strobe II:

The second strobe mode is an alternating or "oscillating" strobe, switching between 8.3Hz and 15.9Hz every 2 seconds. Here is a blow-up of the two frequencies:

Hi-Flash:

Hi-Flash is basically a full power slow strobe/beacon mode. Frequency was a reasonable 2.3Hz in my testing.

SOS I:

The "fast" SOS signals the full SOS sequence (dot-dot-dot, dash-dash-dash, dot-dot-dot) in just over 2 secs. These seems unusually quick to me.

SOS II:

In contrast, the "slow" SOS takes just under 2 seconds just do the "S" (i.e. dot-dot-dot), and about 2.5 seconds to do the "O" (i.e., dash-dash-dash), with >5 secs in-between each sequence. Personally, this seems far more useful than the rather frenetic initial SOS mode.

Beacon:

Beacon is a slow full output burst that is 2 secs long, re-occurring every 20 secs (i.e., a very slow beacon).

Lo-Flash:

Lo-Flash is a lower output, slower frequency strobe/beacon than Hi-Flash. It's hard to see on the traces above (due to the relatively low output), but I measured a frequency of ~0.6 Hz.

Standby Drain

A standby current drain is inevitable on these types of lights, due to the electronic switch in the head/tail.

My two MX25L2 samples (which had custom 3.7V 32650 Li-ions in series) measured in at ~160 and ~190uA, translating into 4.3 and 3.6 years respectively on their stock Eagletac cells.

For the MX25L4, the wiring is a little different. The battery arrangement is 2s2p, with a standby drain of ~106uA on either channel pair (regardless of whether or not the other pair is loaded). For 3400mAh 18650 batteries, that would translate into 3.7 years before they would be fully drained. So overall current drain is pretty equivalent between the MX25L2 and MX25L4 series  and not much of a concern.

That said, you are not able to easily lock out the MX25L4 series, to prevent accidental activation. I recommend you remove the batteries from the light when not in regular use.

Beamshots:

And now, what you have all been waiting for. All lights are on their respective battery sources, about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance used on the stock lights (to minimize tint differences), and Daylight white balance used on the V54 modded lights.

Let's start with a comparison of the MX25L4 Turbo to the MX25L2 series lights. The fourth image in the series below is the standard-head version of the MX25L2 SST-90.

As always, it's hard to tell much about peak intensity throw at such ridiculously close distances. The most obvious observation is that the MX25L4 Turbo has basically the same beam pattern as the MX25L2 Turbo (which is not surprising, given their virtually identical heads). I did see a slightly more pronounced corona artifact on my MX25L4 sample, but that really just reflects precise height/focusing of the reflector.

This means that the MX25L2 Turbo SBT-70 sample above should give you a very good idea what to expect should you opt to get the MX25L4 Turbo with this same emitter.

And now the MX25L4 Turbo compared to some of the competition.

The MX25L4 Turbo is fairly similar to the Olight SR95, although max output and throw are a touch higher on the Eagletac offering (you can't see it at the exposures and distances above  scroll down for direct beam measures).

Compared to my recent PDT-equipped Vinh-modded lights (K50vn and TK61vn V1), the MX25L4 Turbo certainly has more output. But the large die SST-90 can't really match a maximally-driven dedomed XM-L2 for peak throw.

To compare better, let's head outdoors. For outdoor shots, these are done in the style of my earlier 100-yard round-up review. Please see that thread for a discussion of the topography (i.e. the road dips in the distance, to better show you the corona in the mid-ground).

Here you can see that the MX25L2/L4 Turbo SST-90 models produce more light and throw than the Olight SR95. But there really isn't a difference between the MX25L2 and MX25L4 Turbo models themselves  anything you see above is just an aiming difference when holding the lights for these shots.

Scroll down for direct beam measurements.

Testing Method:

All my output numbers are relative for my home-made light box setup, as described on my flashlightreviews.ca website. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for any extended run Lo/Min modes (i.e. >12 hours) which are done without cooling.

Previously, I used to use AW 2200mAh protected cells in my 18650 testing - for their excellent consistency and ability to fit and work in any light. I have been testing a variety of brands of protected NCR18650A cells lately (3100mAh capacity), to see if I can provide runtime comparisons that are more relevant to today's cells. This is not as easy as it may sound, since not all brands will fit in all lights. But I have found a range of brands that show good correlations and internal consistency, and will now be moving the 3100mAh cells in all my 18650-class reviews.

Output levels and regulation patterns are basically identical to the MX25L2 Turbo SST-90 tested previously. My 4x3100mAh cells seem to squeeze a bit more runtime than the 2x32650 battery pack, as you would expect given the rated capacity and orientation of the cells (i.e. 2s2p here means 6200mAh total capacity, compared to 6000mAh on the MX25L2). You could get an extra ~10% or so here by using 3400mAh 18650 cells.

As before, these Eagletac lights step-down by 20% on Max after 200secs runtime.

Potential Issues

As with other Eagletac models where output mode is set by the degree the head is tightened, you need to keep all contact surfaces in the head scrupulously clean. Otherwise, you may experience mode switching problems due to contact surface issues. Some users have previously reported issues with stuck pins in the head, but Eagletac has worked to improve their reliability on recent models.

The Turbo version of the MX25L4 is fairly large, and potentially awkward to carry given the lack of a holster. This is a standard issue on "stubby" high-output throw lights (like the Fenix TK61, Supbeam K50, etc.).

Unlike the MX25L2 series lights, no physical lock out is available  you will need to remove the cells to prevent accidental activation. Standby drain remains fairly negligible as before (with up to 4 years before cells would be drained).

There are some beam artifacts in the corona around the hotspot, but these are common on throwy lights using this emitter (due to the precise focusing of the reflector and the design of the SST-90 emitter).

Preliminary Observations

The MX25L4 Turbo is nice addition to the Eagletac line of high-output throw lights.

I always liked the build and interface of the MX25L2 series, and the MX25L4 is very similar. The main difference is the body/handle and battery  instead of an elongated handle with 2x32650 cells in series (with in-light charger) on the L2-series, you get a more traditional "stubby" handle with four standard 18650 cells side-by-side on the L4-series.

My impression is that many people prefer this more traditional MX25L4 build arrangement, and the ability to use commonly available cells (both 18650 Li-ion and primary CR123A). On that point, the 2s2p arrangement here means that you could technically run the MX25L4 on just 2x18650 or 4xCR123A in a pinch (but I would limit yourself to sub-max modes in those cases). The MX25L4 is perhaps more portable than the MX25L2, but I still think you will find it a challenge to carry this size light for any great distance (i.e., there is no holster or shoulder strap).

There have been a few minor tweaks to the classic Eagletac interface, but nothing major. I find the timings to enter auxillary modes somewhat relaxed now (making it easier to accidentally strobe yourself). And the degree of head twist to change modes is reduced from my earlier MX25L2 series lights.

The Turbo head option for MX25L4 matches the overall output and throw of the MX25L2 Turbo lights I've tested previously. As such, you can rely on the SST-90/SBT-70 results from that earlier series when making your choice of emitter on the MX25L4. Basically, opt for the SBT-70 version if you want to maximize throw (at the expense of a bit of overall output).

Whichever emitter you choose, the MX25L4 Turbo series produces a lot of light with extensive throw. Of course, there are plenty of other lights to consider in this general 4x18650 "Turbo" size class - with multiple or larger emitters (for greater flood), or smaller emitters (for even greater relative throw). But the SST/SBT family of Luminus emitters remains strong contenders for that "traditional" throw/spill arrangement in the high-output class.

wow that sst90 is really being drivin qutie hard that light really does not need to be modded. thats very impressive

Yes, Eagletac has always pushed the SST-90/SBT-90/SBT-70 emitters fairly hard on initial max - more so than most other makers. One can only hope the heatsinking is there to match (I would have to leave it to Vinh to comment on that front). But the step-down after 200 secs is a reasonable precaution in that regard - it makes sense that they don't allow it to be reduced by reprogramming on their models with these emitters. And I certainly haven't observed any problems on any of my samples

Thanks for the review Selfbuilt
I wonder if pushing the sst 90 that hard, would not significantly reduce the led lifetime ?

The SST-90 is rated for a max current of 9 amps per the manufacturer, which is likely conservative especially with good heat-sinking. With that in mind, Eagletac is probably not pushing this that much past the rated spec. and that would only be for the period before the step-down. The lifespan of the LED would be minimally affected by that. These LEDs are rated for thousands of hours which nobody would realistically use a flashlight even close to that amount of time. Also, those ratings are not until the death of the LED but a percentage of loss in original output.

Modders on CPF have been pushing Cree LEDs over 200% past their rated max. currents without problems when well heat-sinked. For example, XP-G2 is rated for max 1.5 amps but people have tested these to 8-9 amps before failure.

I ordered one of these from GoingGear. I cant wait to receive and start using mine! Abandoned subway systems, Deserted factory death traps, Garapito Canyon trail, all nothing when you have The properly harnessed power of the Luminus SST-90 in your hands.

olight SR90 and Eagtac MX25L4 Turbo. Only two lights that throws an unbelievable thick white beam for seemingly a far distance. What it lacks in pinpoint 600 meters throw is more than made up for by the thickness of the thick straight white beam.